Design and Synthesis of (13S)‐Methyl‐Substituted Arachidonic Acid Analogues: Templates for Novel Endocannabinoids

Two novel methyl‐substituted arachidonic acid derivatives were prepared in an enantioselective manner from commercially available chiral building blocks, and were found to be excellent templates for the development of (13S)‐methyl‐substituted anandamide analogues. One of the compounds synthesized, namely, (13S,5Z,8Z,11Z,14Z)‐13‐methyl‐eicosa‐5,8,11,14‐tetraenoic acid N‐(2‐hydroxyethyl)amide, is an endocannabinoid analogue with remarkably high affinity for the CB1 cannabinoid receptor.     

Fast Biosynthesis of GFP Molecules: A Single‐Molecule Fluorescence Study

It's not easy being green : Real‐time visualization of labeled ribosomes and de novo synthesized green fluorescent protein molecules using single‐molecule‐sensitive fluorescence microscopy demonstrates that the mutant GFPem is produced with a characteristic time of five minutes. Fluorescence of the fastest GFP molecules appears within one minute (see picture).

     

Inhibitor of fatty acid amide hydrolase normalizes cardiovascular function in hypertension without adverse metabolic effects

The enzyme fatty acid amide hydrolase (FAAH) catalyzes the in vivo degradation of the endocannabinoid anandamide, thus controlling its action at receptors. A novel FAAH inhibitor, AM3506, normalizes the elevated blood pressure and cardiac contractility of spontaneously hypertensive rats (SHR) without affecting these parameters in normotensive rats. These effects are due to blockade of FAAH and a corresponding rise in brain anandamide levels, resulting in CB? receptor-mediated decrease in sympathetic tone. The supersensitivity of SHR to CB? receptor-mediated cardiovascular depression is related to increased G protein coupling of CB? receptors. Importantly, AM3506 does not elicit hyperglycemia and insulin resistance seen with other FAAH inhibitors or in FAAH?/? mice, which is related to its inability to inhibit FAAH in the liver due to rapid hepatic uptake and metabolism. This unique activity profile offers improved therapeutic value in hypertension.     

Simple and Selective Spectrophotometric Method for the Determination of Iron (III) and Total Iron Content, Based on the Reaction of Fe(III) with 1,2-Dihydroxy-3,4-Diketocyclo-Butene (Squaric Acid)

 Squaric acid (1,2-dihydroxy-3,4-diketo-cyclobutene) is used in a specific reaction with Fe(III) for the spectrophotometric determination of Fe(III) and total iron content. The optimization of the experimental parameters leads to the establishment of a simple, fast and accurate analytical method. The analytical procedure includes mixing ammonium squarate (40 mM), prepared in a phthalate buffer solution of pH 2.7, with the sample and measuring the absorbance at 515 nm. The molar absorptivity of the colored product is 3.95×10³ L·mol⁻¹·cm⁻¹, at 515 nm. Calibration graphs for Fe(III) are rectilinear for 0.5–20 mgL⁻¹, with a detection limit of 0.3 mgL⁻¹ and r.s.d. not exceeding 2.5%, for five replicates of a 3.0 mgL⁻¹ standard solution. The method has been successfully applied to the determination of iron (III) and the total iron content after quantitative oxidation of iron (II). The results for several analyzed samples when compared with those acquired by using the FAAS technique, were found to be in satisfactory agreement. Author for correspondence: University of Ioannina, Department of Chemistry, Laboratory of Analytical Chemistry, Ioannina 451 10, Greece. E-mail: panavelt@cc.uoi.gr Received July 27, 2002; accepted December 20, 2002 Published online April 11, 2003     

Synthesis of covalent probes for the radiolabeling of the cannabinoid receptor

The main psychoactive constituent of marijuana, (-)-Delta(9)-tetrahydrocannabinol, produces most of its physiological effects by interacting with the CB1 cannabinoid receptor, a membrane protein belonging to the large superfamily of G-protein coupled receptors. The 3-D structure of the receptor binding site is of value in the design of novel medications for a variety of therapeutic indications. To obtain information on the amino acid residues associated with this binding site, we have designed and synthesized a cannabinergic CB1 ligand prototype carrying an electrophilic isothiocyanato group capable of reacting covalently with amino acid residues bearing thiol or unprotonated amino groups. The ligand also incorporates an iodide atom, which can serve as a high-activity radiolabel. The key step in our synthesis involves a rapid intramolecular Diels-Alder reaction of a transiently formed o-quinone methide, which proceeds stereospecifically with the formation of the tricyclic cannabinoid template. Introduction of the iodo group is the last step in the sequence and is compatible with the use of (125)I-radiolabel.     

Model Investigations for Vanadium-Protein Interactions. Synthetic, Structural, and Physical Studies of Vanadium(III) and Oxovanadium(IV/V) Complexes with Amidate Ligands

Reaction of the amide ligand N-[2-((2-pyridylmethylene)amino)phenyl]pyridine-2-carboxamide (Hcapca) with VCl(3) affords the compound trans-[VCl(2)(capca)] (1), the first example of a vanadium(III) complex containing a vanadium-deprotonated amide nitrogen bond, while reaction of bis(pentane-2,4-dionato)oxovanadium(IV) with the related ligands N-[2-((2-phenolylmethylene)amino)phenyl]pyridine-2-carboxamide (H(2)phepca), 1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzene (H(3)hypyb), and 1,2-bis(2-hydroxybenzamido)benzene (H(4)hybeb) yields the complexes [VO(phepca)] (2), Na[VO(hypyb)].2CH(3)OH (4.2CH(3)OH), and Na(2)[VO(hybeb)].3CH(3)OH (5.3CH(3)OH) respectively. The preparation of the complex {N-[2-((2-thiophenoylmethylene)amino)phenyl]pyridine-2-carboxamido}oxovanadium(IV) (3) has been achieved by reaction of N-(2-aminophenyl)pyridine-2-carboxamide and 2-mercaptobenzaldehyde with [VO(CH(3)COO)(2)](x)(). Oxidation of complex 5.3CH(3)OH with silver nitrate gives its vanadium(V) analogue (8.CH(3)OH), which is readily converted to its corresponding tetraethylammonium salt (10.CH(2)Cl(2)) by a reaction with Et(4)NCl. The crystal structures of the octahedral 1.CH(3)CN, and the square-pyramidal complexes 3, 4.CH(3)CN, 5.2CH(3)OH, and 10 were demonstrated by X-ray diffraction analysis. Crystal data are as follows: 1.CH(3)CN, C(18)H(13)Cl(2)N(4)OV.CH(3)CN M(r) = 464.23, monoclinic, P2(1)/n, a = 10.5991(7) ?, b = 13.9981(7) ?, c = 14.4021(7) ?, beta = 98.649(2)(o), V = 2112.5(3) A(3), Z = 4, R = 0.0323, and R(w) 0.0335; 3, C(19)H(13)N(3)O(2)SV, M(r) = 398.34, monoclinic, P2(1)/n, a = 12.1108(10) ?, b = 19.4439(18) ?, c = 7.2351(7) ?, beta = 103.012(3) degrees, V = 1660.0(4) ?(3), Z = 4, R = 0.0355, and R(w) = 0.0376; 4.CH(3)CN, C(19)H(12)N(3)O(4)VNa.CH(3)CN, M(r) = 461.31, monoclinic, P2(1)/c, a = 11.528(1) ?, b = 11.209(1) ?, c = 16.512(2) ?, beta = 103.928(4)(o), V = 2071.0(5) ?(3), Z = 4, R = 0.0649, and R(w) = 0.0806; 5.2CH(3)OH, C(20)H(10)N(2)O(5)VNa(2).2CH(3)OH, M(r) = 519.31, triclinic, P1, a = 12.839(1) ?, b = 8.334(1) ?, c = 12.201(1) ?, alpha = 106.492(2) degrees, beta = 105.408(2) degrees, gamma = 73.465(2) degrees, V = 1175.6(3) ?(3), Z = 2, R = 0.0894, and R(w) = 0.1043; 10, C(28)H(32)N(3)O(5)V M(r) = 541.52, monoclinic, P2(1)/c, a = 11.711(3) ?, b = 18.554(5) ?, c = 12.335(3) ?, beta = 95.947(9) degrees, V = 2666(2) ?(3), Z = 4, R = 0.0904, and R(w) = 0.0879. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, and electrochemical properties of these complexes. Electron paramagnetic resonance [of oxovanadium(IV) species] and (1)H, (13)C{(1)H}, and (51)V nuclear magnetic resonance [of oxovanadium(V) complex] properties are reported as well. This study represents the first systematic study of vanadium(III), V(IV)O(2+), and V(V)O(3+) species containing a vanadium-deprotonated amide nitrogen bond.     

New copper-mediated O-arylations of phenols with arylstannanes

A novel method for the synthesis of diaryl ethers with phenols and arylstannanes under mild conditions is described. This copper-mediated O-arylation is feasible using DMAP in acetonitrile and is complementary to the use of boronic acids as aryl donors. The reaction is tolerant of a wide range of substituents and sterically hindered coupling partners.     

In Silico Investigation of the Biological Implications of Complex DNA Damage with Emphasis in Cancer Radiotherapy through a Systems Biology Approach

Different types of DNA lesions forming in close vicinity, create clusters of damaged sites termed as “clustered/complex DNA damage” and they are considered to be a major challenge for DNA repair mechanisms resulting in significant repair delays and induction of genomic instability. Upon detection of DNA damage, the corresponding DNA damage response and repair (DDR/R) mechanisms are activated. The inability of cells to process clustered DNA lesions efficiently has a great impact on the normal function and survival of cells. If complex lesions are left unrepaired or misrepaired, they can lead to mutations and if persistent, they may lead to apoptotic cell death. In this in silico study, and through rigorous data mining, we have identified human genes that are activated upon complex DNA damage induction like in the case of ionizing radiation (IR) and beyond the standard DNA repair pathways, and are also involved in cancer pathways, by employing stringent bioinformatics and systems biology methodologies. Given that IR can cause repair resistant lesions within a short DNA segment (a few nm), thereby augmenting the hazardous and toxic effects of radiation, we also investigated the possible implication of the most biologically important of those genes in comorbid non-neoplastic diseases through network integration, as well as their potential for predicting survival in cancer patients.